Unit Types

ADU vs. JADU: What Are The Key Differences?

May 23, 2022

Given the rising housing prices in California, people are looking for new ways to build affordable living space, whether for themselves or tenants. Many are turning to accessory dwelling units (ADUs) and junior accessory dwelling units (JADUs) to expand the livable space on their properties, whether to bring in extra income or house an older relative. However, these two unit types are not quite the same: They each have their own requirements and specifications. In this article, you’ll learn about the key ADU vs. JADU differences so you can decide whether JADUs are a good option for your property.

What does JADU mean in real estate?

A junior accessory dwelling unit (JADU) is an independent living unit that’s a maximum of 500 square feet. It’s attached to your existing single-family home and involves the addition of no more than 150 square feet to your property. This type of unit is a converted portion of your home and is essentially a smaller version of a standard ADU.

5 key differences between an ADU and JADU

There are a few key characteristics that differentiate an ADU from a JADU, including:

1. Size

As JADUs are smaller ADUs, these junior units have less livable space than that of standard ADUs. JADUs can’t be more than 500 square feet no matter the size of the single-family residence to which the unit is attached. 

ADUs, on the other hand, can range from 300 to 1,200 square feet or more. If attached to the main dwelling on a property, they can take up no more than 50 percent of the square footage of the existing home.

2. Cost

Because a JADU is part of the main home, it can cost less to add than an ADU. Adding a JADU can be as simple as converting an attached garage into a liveable space. However, there may be costs associated with extending plumbing and additional electric connections for a garage JADU. That can make JADUs more expensive than you might have expected. Building an ADU isn’t always that much more expensive, and there are ways you can lower your costs.

There are some options to help lower the cost of adding an ADU to your property. The main one is installing a prefab ADU constructed off-site instead of choosing custom stick-builds. After all, the price of custom ADU construction can range between $250 and $500 per square foot. Offsite construction units instead arrive at a nearly fixed cost, and they make much more attractive rental options than JADUs. That means you can more quickly recoup your costs – and then some – with an ADU. ADUs might be the less costly option in the long run.

3. Requirements

Though both types of accessory structures are classified as livable spaces, they each have their own criteria. An ADU must have a private eating area and bathroom in the unit. In some cases, an ADU that’s attached to the main home will need its own entrance aside from that of the main house. Local ordinances might also require the unit to have a parking space dedicated to its residents.

Interior living space containing a kitchen, dining and living room area, leading to a front door.
Photo by Jed Owen on Unsplash

A JADU needs its own kitchen, but the unit can share a bathroom with the main house. A JADU also needs a separate entrance. In some cases, a local ordinance might require you to have replacement parking if a JADU is a converted garage.

4. Development

Since a JADU is attached to the main home, you can easily add one of these units to your property. Simply convert an existing area in your home into a space that meets all the above JADU requirements. You won’t add any constructed space to your home – you’ll just modify a space in your home to make it livable.

An ADU can either be a separate unit or attached to the main home. You can build an attached ADU as an add-on to the existing structure or a conversion of a larger area, such as a full basement. You can build a detached ADU as new construction on your property or construct a prefab ADU. The latter is often the better option – and it’s always the more affordable one – because they’re constructed off-site with little disruption to your daily life.

5. Renting out

If you’re planning to add a JADU to your home, you have a few options available for how you can use your newly renovated space. You might decide to live in the space yourself, house in-laws there, or generate some rental income through tenants. If you decide to rent out your JADU, it’s important to note that many jurisdictions require the house to be owner-occupied. That means you’ll need to live in the rest of your home while a tenant is renting your JADU.

ADUs, on the other hand, don’t have owner-occupancy requirements. That’s due to a California law that went into effect in 2022. This law bars local agencies from requiring ADU owners to inhabit either their ADU or their main house if they’re renting out either. With this law in place, you could rent out both your ADU and your main house, unless you’re also renting out a JADU. In this case, you would have to live in the main home.

In many cases, California law doesn’t allow you to rent out either your ADU or JADU for fewer than 30 days at a time. However, you can apply for an exception based on certain requirements your home must meet and the number of days you occupy your home.

Can I have an ADU and a JADU?

Yes, you can have an ADU and a JADU on your property. You can also rent both of these spaces to tenants simultaneously, but state law would require you to live in the main home.

A new ADU with Spacial

There are several key elements that differentiate ADUs from JADUs. But while these units have different specifics, they can both be valuable additions to your property. That said, an ADU will generally be more flexible for your property and your goals. When you’re ready to start bringing your dream to life, Spacial is here to help you through the entire process.

Living room and kitchen in Spacials One Bedroom ADU
Photo by Spacial

Here at Spacial, we’ll handle the entire ADU process from start to finish. That means creating permit sets, obtaining city permits, preparing your site, foundation, and utilities, and installing the unit. It also means furnishing the unit, installing the appliances, and generally getting it ready to go. Plus, all the construction happens off-site, so you won’t have to worry about loud construction in your backyard for months on end. 

Once your unit is ready, we’ll deliver it from our factory to your property. And in less than a day, your ADU will be right in place. Contact Spacial today to get started on your dream ADU.